Re: Linux 6.18-rc1

[Guenter Roeck]

On 10/15/25 10:28, Liam R. Howlett wrote:
> + Cc Vlastimil, as you are indicating the slab merge.
>
>
> * Guenter Roeck <linux@xxxxxxxxxxxx> [251015 06:02]:
> > On Mon, Oct 13, 2025 at 09:46:44PM -0700, Guenter Roeck wrote:
> > > On Mon, Oct 13, 2025 at 10:08:26AM -0700, Guenter Roeck wrote:
> > > > On Sun, Oct 12, 2025 at 02:04:32PM -0700, Linus Torvalds wrote:
> > > > > Two weeks have passed, and 6.18-rc1 has been tagged and pushed out.
> > > > >
> > > > > Things look fairly normal: size-wise this is pretty much right in the
> > > > > middle of the pack, and nothing particular stands out in the shortlog
> > > > > of merges this merge window appended below. About half the diff is
> > > > > drivers, with the res being all over: vfs and filesystems, arch
> > > > > updates (although much of that is actually devicetree stuff, so it's
> > > > > arguably more driver-related), tooling, rust support etc etc.
> > > > >
> > > > > This was one of the good merge windows where I didn't end up having to
> > > > > bisect any particular problem on nay of the machines I was testing.
> > > > > Let's hope that success mostly translates to the bigger picture too.
> > > >
> > > > Test results don't look that good, unfortunately.:
> > > ...
> > > > Qemu test results:
> > > > 	total: 609 pass: 581 fail: 28
> > > > Failed tests:
> > ...
> > > > 	sheb:rts7751r2dplus_defconfig:initrd
> > > > 	sheb:rts7751r2dplus_defconfig:ata:ext2
> > > > 	sheb:rts7751r2dplus_defconfig:usb:ext2
> > > > Unit test results:
> > > > 	pass: 655208 fail: 0
> >
> > Update on the sheb (SH4 big endian) failures below.
>
> What is the qemu line you use and the memory configuration of that qemu,
> or is this real hardware?
qemu. I tried 6.2.0, 10.0.5, and 10.1.1. Sample command line:

qemu-system-sh4eb -M r2d -kernel arch/sh/boot/zImage \
	-append "console=ttySC1,115200 noiotrap" \
	-serial null -serial stdio -monitor null -nographic -no-reboot

initrd or root file system doesn't really matter because qemu exits
almost immediately.

> Are there sh4 configs that pass?

little endian - all
big endian - none

> It's a bit odd it says "fail: 0" here, Is this message about something
> else?

This are unit (KUNIT) test results. All 655208 executed unit tests passed.
Unit tests not executed because the image crashed or because qemu died are not
counted as failed.

...

> > # bad: [ba9dac987319d4f3969691dcf366ef19c9ed8281] Merge tag 'libnvdimm-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
> > # good: [e5f0a698b34ed76002dc5cff3804a61c80233a7a] Linux 6.17
> > git bisect start 'HEAD' 'v6.17'
> > # good: [58809f614e0e3f4e12b489bddf680bfeb31c0a20] Merge tag 'drm-next-2025-10-01' of https://gitlab.freedesktop.org/drm/kernel
> > git bisect good 58809f614e0e3f4e12b489bddf680bfeb31c0a20
> > # bad: [8804d970fab45726b3c7cd7f240b31122aa94219] Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> > git bisect bad 8804d970fab45726b3c7cd7f240b31122aa94219
> > # good: [30c3055f9c0d84a67b8fd723bdec9b1b52b3c695] xsk: wrap generic metadata handling onto separate function
> > git bisect good 30c3055f9c0d84a67b8fd723bdec9b1b52b3c695
> > # good: [f79e772258df311c2cb21594ca0996318e720d28] Merge tag 'media/v6.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
> > git bisect good f79e772258df311c2cb21594ca0996318e720d28
> > # good: [f1455695d2d99894b65db233877acac9a0e120b9] Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
> > git bisect good f1455695d2d99894b65db233877acac9a0e120b9
> > # good: [a16c46c2402026162111ed9fd1fc28d25223443e] dma-remap: drop nth_page() in dma_common_contiguous_remap()
> > git bisect good a16c46c2402026162111ed9fd1fc28d25223443e
> > # good: [a5883fa94295f1ef2473eadd84cc1e24dab9ae18] selftests/mm: gup_tests: option to GUP all pages in a single call
> > git bisect good a5883fa94295f1ef2473eadd84cc1e24dab9ae18
> > # good: [08498be43ee676d8a5eefb22278266322578a3e0] mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL
> > git bisect good 08498be43ee676d8a5eefb22278266322578a3e0
> > # good: [719a42e563bb087758500e43e67a57b27f303c4c] maple_tree: Convert forking to use the sheaf interface
> > git bisect good 719a42e563bb087758500e43e67a57b27f303c4c
> > # good: [b9120619246d733a27e5e93c29e86f2e0401cfc5] Merge series "SLUB percpu sheaves"
> > git bisect good b9120619246d733a27e5e93c29e86f2e0401cfc5
> > # bad: [24d9e8b3c9c8a6f72c8b4c196a703e144928d919] Merge tag 'slab-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
> > git bisect bad 24d9e8b3c9c8a6f72c8b4c196a703e144928d919
> > # good: [83382af9ddc3cb0ef43f67d049b461720ad785e6] slab: Make slub local_(try)lock more precise for LOCKDEP
> > git bisect good 83382af9ddc3cb0ef43f67d049b461720ad785e6
> > # good: [af92793e52c3a99b828ed4bdd277fd3e11c18d08] slab: Introduce kmalloc_nolock() and kfree_nolock().
> > git bisect good af92793e52c3a99b828ed4bdd277fd3e11c18d08
> > # good: [ca74b8cadaad4b179f77f1f4dc3d288be9a580f1] Merge series "slab: Re-entrant kmalloc_nolock()"
> > git bisect good ca74b8cadaad4b179f77f1f4dc3d288be9a580f1
> > # good: [07fdad3a93756b872da7b53647715c48d0f4a2d0] Merge tag 'net-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
> > git bisect good 07fdad3a93756b872da7b53647715c48d0f4a2d0
> > # first bad commit: [24d9e8b3c9c8a6f72c8b4c196a703e144928d919] Merge tag 'slab-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
> >
> > I had to revert commit 719a42e563bb ("maple_tree: Convert forking to use
> > the sheaf interface") and commit af92793e52c3 ("slab: Introduce
> > kmalloc_nolock() and kfree_nolock()") in the 'slab-for-6.18' branch to fix
> > the problem. The first patch can not be reverted in mainline since other
> > patches depend on it.
>
> Both 719a42e563bb and af92793e52c3 are listed as good in your bisect
> above.  Why are the two commits you name as the cause listed as 'good'?
>
> What did you revert to get sh4 to work, and from which git branch?
>
> What do you mean "can not be reverted in mainline"?  And which is "the
> first patch", I'm assuming the first one you listed (719a42e563bb)?

I checked out a test branch at 24d9e8b3c9c, rebased it on top of
24d9e8b3c9c8a6~1 (07fdad3a93756b8), and ran another bisect. Results:

# bad: [c5e19dc4c1db098456ee6a924e276a26e692f26c] slab: Introduce kmalloc_nolock() and kfree_nolock().
# good: [07fdad3a93756b872da7b53647715c48d0f4a2d0] Merge tag 'net-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
git bisect start 'HEAD' '07fdad3a93756b872da7b53647715c48d0f4a2d0'
# good: [10f17a5a3befa328bd9a78ca6b799dd1933f108b] maple_tree: remove redundant __GFP_NOWARN
git bisect good 10f17a5a3befa328bd9a78ca6b799dd1933f108b
# good: [f97515baad5efa6e1963abd37188fad42515edc8] maple_tree: Replace mt_free_one() with kfree()
git bisect good f97515baad5efa6e1963abd37188fad42515edc8
# bad: [4df642aa2128c2c346f9c945bddbae37c59bba82] locking/local_lock: Introduce local_lock_is_locked().
git bisect bad 4df642aa2128c2c346f9c945bddbae37c59bba82
# good: [a20be9b8014abfe68acc2efd81bfb5d2dd4eaf34] maple_tree: Prefilled sheaf conversion and testing
git bisect good a20be9b8014abfe68acc2efd81bfb5d2dd4eaf34
# bad: [40696586bc008ad34db8135c35ec4b459691af3c] maple_tree: Convert forking to use the sheaf interface
git bisect bad 40696586bc008ad34db8135c35ec4b459691af3c
# good: [8387347ae261c5e74e9db3f73b91d47f11f8d6f8] maple_tree: Add single node allocation support to maple state
git bisect good 8387347ae261c5e74e9db3f73b91d47f11f8d6f8
# first bad commit: [40696586bc008ad34db8135c35ec4b459691af3c] maple_tree: Convert forking to use the sheaf interface

Reverting just 40696586bc008 in that branch didn't help. So I reverted "slab: Introduce
kmalloc_nolock() and kfree_nolock()" in that branch as well, and the image started
passing.
In mainline, 719a42e563bb ("maple_tree: Convert forking to use the sheaf interface")
can be reverted, but trying to revert af92793e52c3 results in:

CONFLICT (content): Merge conflict in mm/slub.c

Guenter